U.S. patent application number 15/548741 was filed with the patent office on 2018-02-01 for electronic package that includes multi-layer stiffener.
The applicant listed for this patent is Intel Corporation. Invention is credited to Rajendra C. Dias, Manish Dubey, Patrick Nardi, Srikant Nekkanty.
Application Number | 20180033741 15/548741 |
Document ID | / |
Family ID | 56848410 |
Filed Date | 2018-02-01 |
United States Patent
Application |
20180033741 |
Kind Code |
A1 |
Dubey; Manish ; et
al. |
February 1, 2018 |
ELECTRONIC PACKAGE THAT INCLUDES MULTI-LAYER STIFFENER
Abstract
An electronic package that includes a substrate and a die
attached to the substrate. The electronic package further includes
a stiffener that is attached to the substrate adjacent to the die.
The stiffener is formed of a first layer made from one material and
a second layer made from a different material.
Inventors: |
Dubey; Manish; (Chandler,
AZ) ; Nekkanty; Srikant; (Chandler, AZ) ;
Dias; Rajendra C.; (Phoenix, AZ) ; Nardi;
Patrick; (Scottsdale, AZ) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Intel Corporation |
Santa Clara |
CA |
US |
|
|
Family ID: |
56848410 |
Appl. No.: |
15/548741 |
Filed: |
February 12, 2016 |
PCT Filed: |
February 12, 2016 |
PCT NO: |
PCT/US2016/017788 |
371 Date: |
August 3, 2017 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62127499 |
Mar 3, 2015 |
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H01L 23/585 20130101;
H01L 23/562 20130101; H01L 2924/3511 20130101; H01L 23/49838
20130101; H01L 23/16 20130101; H01L 23/498 20130101 |
International
Class: |
H01L 23/00 20060101
H01L023/00; H01L 23/498 20060101 H01L023/498; H01L 23/58 20060101
H01L023/58 |
Claims
1-20. (canceled)
21. An electronic package comprising: a substrate; a die attached
to the substrate; a stiffener attached to the substrate adjacent to
the die, wherein the stiffener is formed of a first layer made from
one material and a second layer made from a different material.
22. The electronic package of claim 21, wherein the stiffener
surrounds the die.
23. The electronic package of claim 21, wherein the stiffener is
secured to the substrate with a conductive adhesive, wherein the
first layer of the stiffener engages the conductive adhesive and
the first layer is formed of an electrically conductive
material.
24. The electronic package of claim therein the first material has
a first coefficient of thermal expansion (CTE) and the second
material has a lower CTE than the first material, wherein the
stiffener has a bending moment that is substantially opposite to a
warpage of the electronic package when a temperature change is
applied to the electronic package.
25. The electronic package of claim 21, wherein the stiffener has a
substantially uniform cross-section.
26. The electronic package of claim 21, wherein the first layer is
the same size as the second layer.
27. The electronic package of claim 21, wherein the first layer has
a different thickness than the second layer.
28. The electronic package of claim 21, wherein the first layer is
aluminum and the second layer is stainless steel.
29. The electronic package of claim 21, wherein the stiffener
includes a third layer made from a different material than the
first layer and the second layer.
30. An electronic package comprising: a substrate; a die attached
to the substrate; a stiffener formed of a first layer made from a
conductive material and a second layer made from a different
material; and a conductive adhesive that secures the substrate to
the first layer of the stiffener.
31. The electronic package of claim 30, wherein the stiffener
surrounds the die.
32. The electronic package of claim 30, wherein the stiffener is
concentric with the die.
33. The electronic package of claim 30, wherein the substrate
includes a ground plane and the conductive adhesive electrically
connects the first layer of the stiffener to the ground plane.
34. The electronic package of claim 30, wherein an upper surface of
the substrate includes a solder resist and the ground plane is
exposed through the solder resist.
35. The electronic package of claim 30, wherein the first layer is
bonded to the second layer.
36. The electronic package of claim 30, wherein the stiffener has a
substantially uniform cross-section, and wherein the first layer is
the same size as the second layer.
37. The electronic package of c a 30, wherein the first layer is
aluminum and the second layer is stainless steel.
38. An electronic package comprising: a substrate; a die attached
to the substrate; a stiffener attached to the substrate such that
the stiffener surrounds the die, wherein the stiffener is formed of
an aluminum layer and a second stainless steel layer made from a
different material, wherein the stiffener has a substantially
uniform cross-section, and wherein the aluminum layer is the same
size as the stainless steel layer.
39. The electronic package of claim 38, wherein the substrate
includes a ground plane and a conductive adhesive that secures the
aluminum layer of the stiffener to the ground plane such that the
aluminum layer of the stiffener is electrically connected to the
ground plane.
40. The electronic package of claim 39, wherein an upper surface of
the substrate includes a solder resist and the ground plane is
exposed through the solder resist.
Description
CLAIM OF PRIORITY
[0001] This patent application claims the benefit of U.S.
Provisional Patent Application No. 62/127,499, filed Mar. 3, 2015,
entitled "ELECTRONIC PACKAGE AND METHOD OF CONNECTING A FIRST DIE
TO A SUBSTRATE TO FORM AN ELECTRONIC PACKAGE", which is
incorporated by reference herein in its entirety.
TECHNICAL FIELD
[0002] Embodiments described herein generally relate to an
electronic package that includes a multi-layer stiffener.
BACKGROUND
[0003] Minimizing transistor size in order to keep up with Moore's
law continually requires reducing first level interconnect (FLI)
pitch and bump size. In addition, using advanced dielectrics has
often resulted in utilizing low-k and extremely low-k materials in
silicon.
[0004] The combination of these factors results in higher
sensitivity to stress during assembly and thermo-mechanical stress.
Therefore, with each new technological advancement, solutions for
reducing thermo-mechanical stress become significantly more
important.
[0005] The thickness of semiconductor devices has been shrinking
with the advent of small form factor devices such as smartphones
and tablets. As a result, coreless packaging is gaining more
attention for small form factor devices. The absence of a core in
the substrate of electronic packages typically implies that there
is relatively higher warpage for such conventional packages.
[0006] One other advancement in packaging technology has been in
the area of ball grid array (BGA) pitch reduction, which is often
capable of obtaining smaller form factors. The combination of
coreless packaging and reduced BGA pitch requires very tight peak
to valley warpage control of the electronic package in order to
fabricate such electronic packages using an efficient surface mount
(SMT) process.
[0007] Two of the solutions that are commonly employed used to
overcome the warpage problem are to use (a) molded underfill (MUF)
and (b) a stiffener. The thickness of the MUF and the stiffener is
driven by the thickness of the dice that form the electronic
package.
[0008] These existing solutions are often able to provide
sufficient process control for electronic packages where the die
thickness is .about.300 microns or greater. However, these existing
solutions are often unable to provide sufficient process control
(i.e., too much warpage) for electronic packages as the die
thickness becomes smaller (e.g., gets closer to 100-200
microns).
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] The following description and the drawings sufficiently
illustrate specific embodiments to enable those skilled in the art
to practice them. Other embodiments may incorporate structural,
logical, electrical, process, and other changes. Portions and
features of some embodiments may be included in, or substituted
for, those of other embodiments. Embodiments set forth in the
claims encompass all available equivalents of those claims.
[0010] FIG. 1 shows the changes in peak-to-valley warpage as a
function of die thickness.
[0011] FIG. 2 shows modeling data that demonstrates where using
bimetallic material stiffeners may provide improved warpage control
during SMT of thin dice.
[0012] FIG. 3 shows modeling data that demonstrates where even
after reducing the width of the stiffener a bimetallic stiffener,
the warpage may be less than a full width monolithic stiffener.
[0013] FIG. 4 shows that the materials for the bimetallic stiffener
may be chosen to form chemical/metallurgical joints with a
conductive adhesive.
[0014] FIG. 5 shows the cross-sectional view of an example
electronic package.
[0015] FIG. 6 shows another form of the electronic package shown in
FIG. 4.
[0016] FIGS. 7A-7B shows example exaggerated room temperature and
high temperature warpage on a bimetallic stiffener system.
DESCRIPTION OF EMBODIMENTS
[0017] The following description and the drawings sufficiently
illustrate specific embodiments to enable those skilled in the art
to practice them. Other embodiments may incorporate structural,
logical, electrical, process, and other changes. Portions and
features of some embodiments may be included in, or substituted
for, those of other embodiments. Embodiments set forth in the
claims encompass all available equivalents of those claims.
[0018] Orientation terminology, such as "horizontal," as used in
this application is defined with respect to a plane parallel to the
conventional plane or surface of a wafer or substrate, regardless
of the orientation of the wafer or substrate. The term "vertical"
refers to a direction perpendicular to the horizontal as defined
above. Prepositions, such as "on," "side" (as in "sidewall"),
"higher," "lower," "over," and "under" are defined with respect to
the conventional plane or surface being on the top surface of the
wafer or substrate, regardless of the orientation of the wafer or
substrate.
[0019] The electronic packages and methods described herein may
address issues associated with maintaining warpage control on
thinner dice with tighter BGA pitch. The basic principle is based
on the CTE mismatch, which is what drives warpage in the first
place.
[0020] The electronic packages and methods described herein use a
bimetallic two-material stiffener which not only provides stiffness
when the packages warps but also provides an opposing moment at
higher temperatures to further reduce warpage. The opposing moment
will counter the high temperature warpage of the electronic
package, thereby reducing the mean warpage of the entire
package.
[0021] Modeling data is presented in FIG. 1 that illustrates where
warpage control gets worse as stiffeners become thinner on the same
electronic package. Specifically, FIG. 1 shows the changes in
peak-to-valley warpage as a function of die thickness. It is
important to note that the thickness of the stiffener in this
modeling was assumed to be the same as the die thickness.
[0022] As shown in FIG. 1, for the same package dimensions, the
warpage gets worse as the dice get thinner. As an example, the
target mean warpage TMW1 and the upper spec limit USL1 for 0.4 mm
BGA pitch and 0.035 BGA pitch as shown in FIG. 1. In addition, the
target mean warpage TMW1 and upper spec limit USL1 for 0.4 mm BGA
pitch is 80 and 140 .mu.m respectively. While this is achievable
for 270 .mu.m dice as seen in FIG. 1, it becomes more difficult for
thinner dice.
[0023] Apart from the thickness of the die, BGA pitch reduction to
0.35 mm requires the target mean warpage TMW2 to drop down to 50
.mu.m and the upper spec limit USL2 to drop down to 110 .mu.m. This
modeling data clearly shows that conventional stiffeners (e.g.,
conventional stainless steel stiffeners) do not provide the warpage
control that is required for electronic packages with reduced die
thickness and reduced BGA pitch.
[0024] The bimetallic two-material stiffener may provide warpage
control on future thin die electronic packages that require tighter
BGA pitch. FIG. 2 shows modeling data that demonstrates where using
bimetallic two-material stiffeners may provide improved warpage
control during SMT of thin dice.
[0025] Specifically, FIG. 2 shows as examples 25.degree. C. and
greater than 200.degree. C. P-V the peak-to-valley warpage for (a)
steel; (b) aluminum; and (c) steel/aluminum bimetallic strip and
warpage. FIG. 2 further shows a significant reduction in
peak-to-valley warpage (.about.35%) when using a bimetallic
two-material stiffener as compared to a monolithic stiffener.
[0026] As an example, a peak may equal the largest deflection in
one direction and a valley may equal the largest deflection in an
opposite direction. Deflection as measured may be considered the
distance that the peak (or valley) is out of plane from a not
deflected state of the electronic package.
[0027] The bimetallic stiffener materials and thicknesses may be
selected for different die thickness such that the bimetallic
two-material stiffener height does not exceed the die thickness.
Therefore, the backside of the die may be exposed for thermal
attachment to a substrate (e.g., to a heat sink).
[0028] As discussed above, the modeling data as shown in FIG. 2
demonstrates a considerable improvement for high temperature
warpage (35% better than steel and 45% better than aluminum). The
room temperature warpage is also considerably better than the two
monolithic stiffeners (35% better than steel and 7% better than
aluminum). The modeling assumed equal thickness (100 .mu.m) for
both of the metals in the bimetallic case for the sake of
simplicity.
[0029] In some forms, further reduction in warpage may be achieved
by tailoring the thickness and other material properties of the two
metals. As an example, two materials may be selected with different
CTE where the correct one is put on top so that the stiffener
incorporates a bending moment that counters the expected warpage of
the electronic package upon exposure to different temperatures. In
addition, even better performance may be achieved by using
multilayered metallic stiffener systems.
[0030] In addition to providing better warpage control for thin
dice, the bimetallic two-material stiffener may also require a
smaller footprint as compared to monolithic stiffeners. This
smaller footprint may provide a smaller keep out zone (KOZ) for
stiffeners. The smaller KOZ reduction may reduce the form factor of
the electronic package without compromising warpage control of the
electronic package.
[0031] FIG. 3 shows the change in peak-to-valley warpage by
reducing the width of the stiffener for bimetallic (e.g., aluminum
& stainless steel) and monolithic (e.g., stainless steel)
stiffeners. It should be noted that the peak-to-valley warpage for
the narrow bimetallic two-material stiffener is still lower than
the warpage for the full monolithic stiffener.
[0032] Specifically, the modeling data in FIG. 3 shows that even
after reducing the width of the two-material stiffener by
.about.50%, the delta warpage (25-260.degree. C.) of the bimetallic
two-material stiffener is less than a full width monolithic
stiffener. FIG. 3 shows the modeling data obtained on a 170 .mu.m
thin die/stiffener. FIG. 3 further illustrates that the delta
warpage (25-260.degree. C.) for the narrow (650 .mu.m on all sides)
bimetallic two-material stiffener is lower than the warpage of the
full (1250 .mu.m on 2 sides and larger on other 2 sides) monolithic
stiffener.
[0033] In some forms, the bimetallic two-material stiffener may be
used to lower the high temperature warpage of the electronic
package. Lowering the high temperature warpage of the electronic
package may be achieved by joining the bimetallic sheets at higher
temperature, which will produce stiffeners that are flat at the
joining temperature. While joining the bimetallic sheets at higher
temperature may not change the amount of warpage over a range of
temperatures, it may provide another way to control warpage
depending on the electronic package design and the desired warpage
requirements.
[0034] In addition, the bimetallic two-material stiffeners
described herein may provide for a stiffener where the stiffener
needs to be grounded to the substrate. FIG. 4 shows that while it
may be difficult to adhere metallic adhesive (e.g., solder) to
stainless steel, the materials for the bimetallic material may be
chosen to form electrical/chemical/metallurgical joints with the
conductive adhesive to facilitate the stiffener conducting
electricity.
[0035] In the example form shown in FIG. 4, the bimetallic
stiffener may provide an added benefit in situations where the
stiffeners needs to be grounded to the substrate. While it is often
difficult to adhere a metallic adhesive (e.g., solder) to stainless
steel, the bimetallic materials may be chosen and arranged to form
electrically conductive joints with the conductive adhesive.
[0036] FIG. 4 is an enlarged view illustrating a portion of an
example electronic package. FIG. 5 illustrates the entire
electronic package for the enlarged portion of the electronic
package shown in FIG. 4.
[0037] As shown in FIGS. 4 and 5, the electronic package 40
includes a substrate 41 and a die 42 (see FIG. 5) attached to the
substrate 41. The electronic package 40 further includes a
stiffener 43 that is attached to the substrate 41 adjacent to the
die 42. The stiffener 43 is formed of a first layer 44 made from
one material and a second layer 45 made from a different
material.
[0038] In some forms, the stiffener 43 entirely surrounds the die
42. In other forms, the stiffener 43 may partially surround the die
42. The determination to whether the stiffener 43 surrounds the
entire die 42 will depend in part on the footprint design of the
electronic package 40 (among other factors).
[0039] In addition, the stiffener 43 may be concentric with the die
42. The stiffener 43 may also be partially concentric with the die
42.
[0040] In some forms, stiffener 43 may have a substantial uniform
cross-section. In other forms, the cross-section of the stiffener
43 may change in size. As an example, two opposing sides of the
stiffener 43 may have one type of cross-section and the other two
opposing sides may have another type of cross-section.
[0041] In addition, the first layer 44 may be the same size as the
second layer 45. It should be noted that forms of the electronic
package 43 are contemplated where the first layer 44 and the second
layer 45 are different sizes.
[0042] In addition, the first layer 44 may have a different
thickness than the second layer 45. In other forms, the first layer
44 may the same thickness as the second layer 45. The relative
thicknesses of the first layer 44 and the second layer 45 will
depend in part on die 42 thickness, package dimensions, and the
available footprint for the stiffener 43 (among other factors).
[0043] In some forms, the first layer 44 may be made of aluminum
and the second layer 45 may be made of stainless steel. In another
form, the first layer 44 may be made of a nickel alloy and the
second material may be made of a manganese-copper-nickel alloy. It
should be noted that a variety of materials are contemplated for
the first layer 44 and the second layer 45. Some of the factors
that determine the selection of the first layer 44 and the second
layer 45 include (i) die thickness; (ii) package dimensions; (iii)
package warpage; (iv) available foot-print of the stiffener 43; (v)
ease of manufacturing; and/or (vi) cost (among other factors).
[0044] FIG. 6 shows another example form of the electronic package
40. In the example electronic package 40 shown in FIG. 6, the
stiffener 43 in the electronic package 40 includes a third layer 46
that is made of a different material than the first layer 44 and
the second layer 45. It should be noted that the relative size and
thicknesses of the first layer 44, the second layer 45 and the
third layer 46 will depend in part on many of the factors described
above.
[0045] As shown in FIGS. 4 and 6, the electronic package 40 may
further include a conductive adhesive 47 that secures the substrate
41 to the first layer 44 of the stiffener 43. First layer 44 is
formed of an electrically conductive material such that the first
layer 44 and the conductive adhesive 47 are electrically connected
together.
[0046] In some forms, the substrate 41 of the electronic package 40
include a ground plane 48 such that the conductive adhesive 47
electrically connects the first layer 44 of the stiffener 43 to the
ground plane 48.
[0047] As shown in FIGS. 4 and 6, an upper surface of the substrate
41 may include a solder resist 49 such that the ground plane 48 is
exposed through the solder resist 49. The degree to which the
ground plane 48 is exposed through the solder resist 49 may depend
in part on the type of conductive adhesive 47 and the size of the
first layer 44 of the stiffener 43 (among other factors).
[0048] In some forms, additional organic and inorganic layers may
be included as part of the solder resist 49. The type solder resist
49 that is included in the electronic package 40 will depend in
part on manufacturing considerations and the types of materials
that are used for the conductive adhesive 47 and the package
substrate 41 (among other factors).
[0049] In some forms, the first layer 44 may be bonded to the
second layer 45 before (or after) the stiffener 43 is attached to
substrate 41. As examples, the first layer 44 may be bonded to the
second layer 45 by laminating (e.g., rolling) the first layer 44 to
the second layer 45 and/or plating the first layer 44 and the
second layer 45 to the other of the first layer 44 and the second
layer 45.
[0050] The stiffener 43 may be configured to oppose the bending
moment of the overall electronic package in order to improve the
peak-to-valley warpage. The relative thickness, co-efficient of
thermal expansion (CTE) and other material properties of the chosen
materials for the stiffener 43 may be selected to provide the
desired warpage properties, especially during SMT of thin dice. As
an example, the CTE, thickness and other material properties of the
first material and the second material may be tailored to provide
an opposing moment to the electronic package warpage, especially at
high temperatures in order to improve overall peak-to-valley
warpage.
WARPAGE EXAMPLE
[0051] Warpage modeling was conducted on a 20.times.20 mm coreless
substrate with a 270 .mu.m thick 10.times.10 mm die. The thickness
and width of the modeled stiffener was 200 .mu.m and 2 mm
respectively.
[0052] FIGS. 7A and 7B show the (a) room temperature and (b) high
temperature warpage on a bimetallic stiffener system. The images
have been exaggerated 30 times to highlight the warpage.
[0053] This overview is intended to provide non-limiting examples
of the present subject matter--it is not intended to provide an
exclusive or exhaustive explanation. The detailed description is
included to provide further information about the electronic
packages.
[0054] To better illustrate the electronic packages disclosed
herein, a non-limiting list of examples is provided here:
[0055] Example 1 includes an electronic package. The electronic
package includes a substrate and a die attached to the substrate. A
stiffener attached to the substrate adjacent to the die, wherein
the stiffener is formed of a first layer made from one material and
a second layer made from a different material.
[0056] Example 2 includes the electronic package of claim 1,
wherein the stiffener surrounds the die.
[0057] Example 3 includes the electronic package of any one of
claims 1-2, wherein the stiffener is secured to the substrate with
a conductive adhesive, wherein the first layer of the stiffener
engages the conductive adhesive and the first layer is formed of an
electrically conductive material.
[0058] Example 4 includes the electronic package of any one of
claims 1-3, wherein the first material has a first coefficient of
thermal expansion (CTE) and the second material has a lower CTE
than the first material, wherein the stiffener has a bending moment
that is substantially opposite to a warpage of the electronic
package when a temperature change is applied to the electronic
package.
[0059] Example 5 includes the electronic package of any one of
claims 1-4, wherein the stiffener has a substantially uniform
cross-section.
[0060] Example 6 includes the electronic package of any one of
claims 1-5, wherein the first layer is the same size as the second
layer.
[0061] Example 7 includes the electronic package of any one of
claims 1-6, wherein the first layer has a different thickness than
the second layer.
[0062] Example 8 includes the electronic package of any one of
claims 1-7, wherein the first layer is aluminum and the second
layer is stainless steel.
[0063] Example 9 includes the electronic package of any one of
claims 1-8, wherein the stiffener includes a third layer made from
a different material than the first layer and the second layer.
[0064] Example 10 includes an electronic package. The electronic
package includes a substrate and a die attached to the substrate. A
stiffener is formed of a first layer made from a conductive
material and a second layer made from a different material, and a
conductive adhesive that secures the substrate to the first layer
of the stiffener.
[0065] Example 11 includes the electronic package of claim 10,
wherein the stiffener surrounds the die.
[0066] Example 12 includes the electronic package of any one of
claims 10-11, wherein the stiffener is concentric with the die.
[0067] Example 13 includes the electronic package of any one of
claims 10-12, wherein the substrate includes a ground plane and the
conductive adhesive electrically connects the first layer of the
stiffener to the ground plane.
[0068] Example 14 includes the electronic package of any one of
claims 10-13, wherein an upper surface of the substrate includes a
solder resist and the ground plane is exposed through the solder
resist.
[0069] Example 15 includes the electronic package of any one of
claims 10-14, wherein the first layer is bonded to the second
layer.
[0070] Example 16 includes the electronic package of any one of
claims 10-15, wherein the stiffener has a substantially uniform
cross-section, and wherein the first layer is the same size as the
second layer.
[0071] Example 17 includes the electronic package of any one of
claims 10-16, wherein the first layer is aluminum and the second
layer is stainless steel.
[0072] Example 18 includes an electronic package. The electronic
package includes a substrate and a die attached to the substrate. A
stiffener attached to the substrate such that the stiffener
surrounds the die, wherein the stiffener is formed of an aluminum
layer and a second stainless steel layer made from a different
material, wherein the stiffener has a substantially uniform
cross-section, and wherein the aluminum layer is the same size as
the stainless steel layer.
[0073] Example 19 includes the electronic package of claim 18,
wherein the substrate includes a ground plane and a conductive
adhesive that secures the aluminum layer of the stiffener to the
ground plane such that the aluminum layer of the stiffener is
electrically connected to the ground plane.
[0074] Example 20 includes the electronic package of any one of
claims 18-19, wherein an upper surface of the substrate includes a
solder resist and the ground plane is exposed through the solder
resist.
[0075] The above detailed description includes references to the
accompanying drawings, which form a part of the detailed
description. The drawings show, by way of illustration, specific
embodiments in which the invention can be practiced. These
embodiments are also referred to herein as "examples." Such
examples can include elements in addition to those shown or
described. However, the present inventors also contemplate examples
in which only those elements shown or described are provided.
Moreover, the present inventors also contemplate examples using any
combination or permutation of those elements shown or described (or
one or more aspects thereof), either with respect to a particular
example (or one or more aspects thereof), or with respect to other
examples (or one or more aspects thereof) shown or described
herein.
[0076] In this document, the terms "a" or "an" are used, as is
common in patent documents, to include one or more than one,
independent of any other instances or usages of "at least one" or
"one or more." In this document, the term "or" is used to refer to
a nonexclusive or, such that "A or B" includes "A but not B," "B
but not A," and "A and B," unless otherwise indicated. In this
document, the terms "including" and "in which" are used as the
plain-English equivalents of the respective terms "comprising" and
"wherein." Also, in the following claims, the terms "including" and
"comprising" are open-ended, that is, a system, device, article,
composition, formulation, or process that includes elements in
addition to those listed after such a term in a claim are still
deemed to fall within the scope of that claim. Moreover, in the
following claims, the terms "first," "second," and "third," etc.
are used merely as labels, and are not intended to impose numerical
requirements on their objects.
[0077] The above description is intended to be illustrative, and
not restrictive. For example, the above-described examples (or one
or more aspects thereof) may be used in combination with each
other. Other embodiments can be used, such as by one of ordinary
skill in the art upon reviewing the above description.
[0078] Also, in the above Detailed Description, various features
may be grouped together to streamline the disclosure. This should
not be interpreted as intending that an unclaimed disclosed feature
is essential to any claim. Rather, inventive subject matter may lie
in less than all features of a particular disclosed embodiment.
Thus, the following claims are hereby incorporated into the
Detailed Description, with each claim standing on its own as a
separate embodiment, and it is contemplated that such embodiments
can be combined with each other in various combinations or
permutations. The scope of the invention should be determined with
reference to the appended claims, along with the full scope of
equivalents to which such claims are entitled.
* * * * *